ABSTRACT
Bemisia tabaci stands out as the most important member of the family Aleyrodidae for its grave impact on tropical and subtropical agriculture. Eggs of B. tabaci are usually laid on the lower surface of leaves. After hatching, the minute first-instar nymphs crawl actively in search of suitable sites for settling down. Although B. tabaci is recognised as an important pest, quantitative data on the damage or economic thresholds are strikingly scant. B. tabaci is highly polyphagous and has been recorded on more than 500 species of plants including numerous field crops, ornamentals and weeds. The sudden violent population explosions of B. tabaci in various parts of the world and gross differences in susceptibility of the same plant species to the whitefly in different locations, suggest the existence of different biotypes of the whitefly. One disturbing factor is that B. tabaci has expanded its range of distribution to new parts of the world, apparently due to human-assisted introduction.
